1. Field of the Invention
This invention relates to attenuating phase shifting photomasks and more particularly to the formation of attenuating phase shifting material using a composite of a first material with a high extinction coefficient and a second material with a high index of refraction to achieve desired optical properties. More particularly the first material is LaNiO .sub.3 and the second material is either TiO.sub.2 or Ta.sub.2 O.sub.5.
2. Description of Related Art
As optical lithography advances to smaller spacings and tighter tolerances phase shifting type photomasks are often used to achieve improved tolerances and pattern edge definition.
U.S. Pat. No. 5,286,244 to Yoo describes methods for making phase shifting photomasks using silicon oxide and silicon nitride materials.
The invention described in this patent application uses the optical properties of (LaNiO.sub.3).sub.x (TiO.sub.2).sub.1-x or (LaNiO.sub.3).sub.x (Ta.sub.2 O.sub.5).sub.1-x oxide absorption composite to form attenuating phase shifting blanks and masks for use in photolithographic processes.